Pneumatic turbine drive control system



May 12, 1959 E. c. PALMENBERG 2,886,048

PNEUMATIC TURBINE DRIVE CONTROL SYSTEM Filed Jan. 20, 1955 4 Sheets-Sheet l QEDW OP 22KB z m2 wmammmma 2: 6528 5 30%. m2 mmswwmma j mOwZwm ommam .Y p f I Y 55 May 12, 1959 E. c. PALMENBERG 2,385,048

PNEUMATIC TURBIYNE DRIVE CONTROL. SYSTEM Filed Jan. 20, 1955 4 Sheets-Sheet 2 ilk,

MOI-4W ATTORNEY May 12, 1959 E. cfPALMENBERG 2,836,043

' PNEUMATIC TURBINE DRIVE CONTROL SYSTEM IN V EN TOR.

EDWARD C. PALMENBERG giw m ATTORNEY May 12, 1959 E. c; PALMENBERG PNEUMATICTURBINE DRIVE CONTROL SYSTEM Filed Jan. 20, 1955 4 Sheets-Sheet 4 gm v .m

*zgsssgon PNEUMATIC niuvncoNmoLsYsTE-M EdwardClPalmenbergNanuet, 'N.Y,, assign-or to Bendix Aviation Corporation, Tetei-boro; NJL, a corporation of Delaware Application January 20,1955, SerialNo. 483,083

{1 Claims; (Cl. 137---27) inventionis concerned with providingnewarid useful improvements in controlling tthe opfiration of; pneumatic turbine it drives. It particularly concerns Ma ,novel and practical pn enmatic tturbine drive i controlsystemthe turbineengine is provided, one of which servestras an emergencycontrolimtheeventvthe other.fails to func-' tion.

:Anotherteatureof the] inventionliesin various valve structures a and r-arrangements whereby the ;flow of .pressureiair that drives the turbine is controlled.

:The invention i further lies in thestmcture, simple or; ganization and arrangement ofthe various elementstofthe control system, and in their cooperative association with oneanother, whereby an-efficient and practicalflturbine drive controlsystemris obtained., 1 a :A general objectqof the inventiontis, thereforelto providevan improved, practical, and elfiientlyoperatingtturbinedrive control 1 system. U t Asmore particular object of the 'inventionis to provide. anhuncomplicated t systern for controlling .the speed ofvaspneuniatic turbinedrive! a t y i Anothero bject, mo ghjpemheias to providesi m ple and efficiently operating valve tstructuresjin tcoqp fra tive association with .one notherto control .the tspeednof a turbinedrive. n y I t The foregdingbbjects and advantages .of the invention will appear he ein .hereinafterfroma ,con'sideration'df thedetailed description which follows, taken together with the accompanying drawings wherein an expressly understood, however, that the drawings are for purposes of illustration anddescription, and are not tolbej construed as defining the .sliniits of the invention.

In the drawings:

Fig. 1 is a schematieviewYshow/ing the trelativenassocitation of; the -various units .of the other; i

Fig. '2 is a longitudinal cross .section [through ,the sturbineldrivetunit;

Fig. 3 is .a siniilartsectionthrough the pressure air Ifiow control unit; i a n p Fig. 4 isKa right endffragmentary view of :Fig. .3; Fig-Sis a left end view ofsFig li, wherein the ballvalve is sectionedgaand y n Fig. 6 is across 1 sectionthrough =the-thydraulic pressure relief valve. a t a 1 lnggeneral, xthe zcontrol: system of fthe. present invention includes a turbine drive unit" adaptedtorbe pneumatically driven by pressure air supplied to it i from a tzsuitable system with one i an-j 2,886,048 Patented l May 12, 1959 source through ,a pressure air "flow control unitf The Associated with 1 this? air: inflow wvalve control: mechanism are a certain .controlsizautomatically (operable by r the ctnr-i bine drive upon the latter attaining an excessive speed;

sure yairzinflow valve:controlqrnechanism, wherebyt-inilowr air to the: flOWl controlnunit is theldsatsar constant pressure.

astmay happen when the outflow pressures :air i controls are. malfunctioning. These associated-controls, whenrop erated, s erve to cut offtthe inflowtsupply of pressureuair to the flow control.unitentire1y,uor:tothe extent required to restore thespeedofithe turbinetonofmall a *In detailing theoper'ation of thesystemLofthespresen invention and the -structures of :thet'cooperating parts thereof," reference is now directed tothe:several drawings.

The tu'rbinedriveuhit 1-of the present invention (Figs! 1, 2;"3 includes a turbine men rber T2 of an I associatedl jet,

aircraft; though it isiln'derstoodthe invention may well'zhe employed. in otherwork situations. The turbine :1 mem tatablemovement in bearings141 carriedwinia properchousing-S. The turbine member is pneumatically ldrivenvby pressure: air ='fed= to i-t through the pressurerair flow :control:.unit6. "The pressure airvflows fromunit-ifi through a connected scroll 7 and ducts 8 to attack the turbine blades, the used air passing out throughian exhaust: duct9.

'The pressure airlflow control unit-"6 (FigMrS) includes an elongated sleeve or cylinder member 10 havingt a r-13111 rality: of inflow sports n11 tthroughmhe wall'thereof, just to thevright of center; An inletiscroll :141lII1OUI1ll6d about the tleft portion s ofrcylinder @1 0 communicates ithrough" ports 11 i with: theiinterior of the cylinder; outletiports 112 communicate the interior rof the scylinder with am outlet SCI'OHCIS mounted about thev right portion. ofcylinde'rill);

Inlet scroll14 providesnaninlettendtlmadlapted foriconnection to a :proper :source of;pressure a-ir s'upply,hnot

shown. .Valvemechanism 18 incorporatedin' the lfiftxfilld of thecylinder regulates the inflow of pressure air: through ports 111.10 thet interion of thecylinder. -;0utlet scrolli 15 embddim ent of th inv nti ji i11 nt d (It ji o'b the inletend of1theiturbinetscrollflr ivalvewmechanism zzurineorporatedlin: the righttend of cylinder 10 regulates thewoutflowsof pressure airr from the interiorvofithe-l eyl:

inderi'through ports 1'2ato1the1 turbine. i t 1 Relative to the structure r of; the 1 outflow pressurenair control valve-"mechanism. 22, the: rightiend oft cylinderikl'll is closed over by a rcrown member :chaving an annular flange t23 which overlaps sanrend wall of cylinder 102 :and is secureduto; the wall ofthe woutlet scroll 15. A 1 crown portion 24 or thefcrown: memberwprojects :axiallyginto cylinder 10 inxspacedmelation:to the wallvof the latter. IHQJthBE'iIlIifiI'IIlOSt end of the :crown is "securely: fitted;;a plug-member :25 carrying an annular flanged-free end r26; Surrounding? the crownkelement and limited betweentfiange z6xandla dishedring 27 is; a compressionmoil spring.

whichnterminates at thecright r edges :Wof ithe iseveral; out+ flow ports 12. The dished ring 27 is fitted in the right end of sleeve 29 and locked to the sleeve by a snap ring 32. Fitted in the left end of the sleeve is a radially perforated cap or dished member 33 that is locked to the sleeve by a snap ring 34. Sleeve member 29 serves as a valve to cover and uncover the outflow ports 12. The arrangement is such that, the coil spring 28 normally tensions sleeve 29 to the right, wherein such position the outflow ports 12 are uncovered by sleeve 29. Moving the cap member 33 to the left will carry sleeve 29 and dished ring 27 along with it against the tension of coil spring 28; this action will draw sleeve 29 over the outflow ports and, according to the extent of such movement, will diminish the outflow of pressure air to the turbine. Coil spring 28 acts to restore the sleeve, as leftward pressure against the cap member 33 is cut off. It is plain that the speed of the turbine will be proportionately curbed with the decrease in pressure air flow. The sleeve member 29 is operated by hydraulic'means, and is governed in its movement by suitable turbine speed sensing means.

The hydraulic means for operating sleeve valve 29 includes a piston cylinder 35, capped at one end by plug member 25. In cylinder 35 reciprocates a piston 36 having a rod 37. The latter is slidable through an axial hole of plug 25, and normally limits against a central wall area 38 of cap member 33. The right end of piston cylinder. 35 communicates with a fitting 39. The piston is driven'by pressure oil pumped by a gear pump 41 (Fig. 2) from a sump section of the housing to fitting 39. Suitable gearing 42 operatively connects the gear pumpto-the turbine drive shaft 3. Communication of the outlet of the gear pump to piston cylinder 35 is normally blocked by-a speed sensing valve 43. Interposed in an oil line 44, between the outlet of the gear pump and an inlet port 55 of the speed sensing valve, is a pressure relief valve 46 (Figs. 1, 6). The latter relieves to sump over passage 40 excessive pump oil pressure developing in line 44.

The speed sensor valve 43 normally blocks pressure oilflow from operating the piston 36 of the pressure inflow control unit 6 during normal speeds of the turbine.- But when the turbine exceeds this normal speed, the speed sensor valve is caused to progressively open. In its structure, the speed sensor valve (Fig. 2) includes a cup member 47' having an axially extending hollow shaft portion 48 which is geared at 49 to the turbine drive shaft'and rotates in a suitable bearing 50. Slidable in the shaft is a valve rod 51 having a headed end 52 that is slidable in cup member 47. Acoil spring 53, limited between acup 54 and the valve head 52, tensions rod 51to the right where the shank of the latter closes over or blocks oii port 55 that communicates the hollow shaft 48 with the gear pump line 44. Suitable adjusting means 56 is provided to adjust the tension of spring 53, as desired. A plurality of equally spaced bellcrank ele-. ments 57 are pivoted in individual slots 58 radially about cup 47. Each bellcrank includes a short arm having a i I roller end 59 that underlies'valve head 52, and .also includes a' weighted fly-arm.61. The operation of the sensor valve 43 and its relation to the gear oil pump 41 is such thatras the turbine speed increases beyond apredesign'ed maximum, the weighted bellcrank arms 61 flyoutward and cause valve rod 51 to be drawn leftward. This action progressively draws a tapered reduced section 62of rod 51 over p'ort55. This opens communication of the gear pump line 44 through port 55, the "interior 'of hollow shaft 48, and a port '63 to the fitting'39 of unit 6 (Fig. 3) and to the associated piston 36. 'A thickened end'64 of the valve rod 51 blocks escape of oil through'the open right end of sensor shaft 48. Pressure oil communicated to piston 36 actuates the latter to move its red '37 against the cap member 33, causing the latter to progressively draw the sleeve element 29 over the outflow ports 12. With this action, the flow of pressure air to drive the turbine is decreased, causing the turbine to decelerate to normal speed. Coil spring 28 acts to progressively restore cap 33 and piston 36 as the flow of pressure oil is again blocked "consequent upon restoration of the valve rod 51. The pressure oil carried to piston 36 is drained to sump as the piston restores through a narrow bleeder line 60 in an adjustable screw 60A, passage 65 and -a sump connecting fitting 66 shown schematically in Fig. 1 and indicated by dotted lines in Fig. 3. It is clear that, as the sensor valve rod 51 is progressively drawn leftward with increasing turbine speed the decline of the tapered surface 62 thereof'increases to progressively provide a greater oil flow through port 63 to the piston 36 and, as a consequence, causes a further closing of the outflow ports 12. It is also clear that, as the turbine speeds above a predetermined rate and decelerates back again with unloading and loading of the turbine, the valve sleeve 29 will oscillate back and forth over the outlet ports 12 to provide a controlled pressure air flow to the turbine. It is to be noted that the left portions of the outlet port 12 are tapered or cut off at an angle. This serves to prevent an abrupt closing off of the air flow therethrough.

Plug 25 through'which the hydraulic piston rod 37 moves is subject to considerable heat that develops in the interior of cylinder 35. The piston cylinder also de-- velops heat in the operation of the piston. The piston. cylinderand the plug are kept cool by circulating the; gear pump fluid over these parts on its return to sump; To this end, a shell 67 surrounds the piston cylinder and provides a space 68 between the two. This shell is se-- cured at one end about plug 25 and is closed over at the In this block is mounted the. fitting 39 which communicates by a passage 70 with. Branching oil? from this passage through a. bleeder line 60 is the narrowed sump return line 65.. p The latter communicates through block 69 with the space: 68' and also with the sump return fitting 66 indicated in: Fig. 3 by dotted lines. Space 68 communicates with the: piston cylinder 35 through a plurality of ports 71. By

other end by a block 69.

the piston.

this arrangement, hydraulic fluid bleeding through the passage 65 circulates in the space 68 about cylinder35 and through the ports 71 to cool both the cylinder and plug 25, and returns to sump by way of the fitting 66.

The pressure air inlet control valve mechanism 18 incorporated in the left end of cylinder 10 serves to maintain a constant inlet pressure air flow through ports 11,

though the air pressure through the inlet scroll 14 may vary. This valve mechanism operates to oscillate over the ports 11, decreasing or increasing the flow of the cylinder 10 accordingly as the pressure through the scroll 14 varies, whereby a constant-pressure flow through ports 11 is provided.

The structure of the valve mechanism 18 includes a crown member 72, a flange 73 of which overlaps the left end wall of cylinder 10 and is secured to the end wall of the intake scroll. The crown member 72 projects axially into cylinder 10 in spaced relation to the wall of the latter. A coil spring 74 surrounds the crown and is tensioned between a stationary flange 75 at one end and a dished ring 76 at the other. Ring 76 is fitted in one end of a valve sleeve 77 that is slidable in the cylinder 10 in contact with the wall of the latter. Ring 76 is locked to the sleeve by a snap ring 78. A perforated cap 79 is fitted in the opposite end of the sleeve and is locked therein by a snap ring 80. The sleeve is tensioned leftward by spring 74 to a position where its right edge is removed from the pressure air inlet ports 11. The coil spring retaining flange 75 is part of a plug 81 that is fitted fast in one end of a piston cylinder 82. The latter is fitted fast in the inner end of crown member 72. The opposite end of piston cylinder 82 is fitted with a plug 83, to which axially connects a fitting 84. Slidable in cylinder 82 is a piston 85. Axially extending from the head and limits againsta central solidarea 93 f cap member *79.-Inl et ports 11- communicate throughperforations 94 of chpnreinber *79 to ;space =95, and through cross holes 96 in-the projectingendof shaft 91- to the cup head 90 of piston 89. The structure is such that, inflow air passing athrough inletscroll l4 -enters the interior of cylinder 10* through ports 11 and=passes from-the interior of cylinder =10 through-ports -12= to attack the turbine. This inlet also passes "through the-perforated cap 79 and the cross holes of hollow shaft 91 tothe piston cup 90. Up toa predesigned force of coil spring-'74, the pressure air "-has no-eifect onpiston 89. .1 -However; 'when Itheintake air pressure exceeds the opposed tension of spring-74; the air acts -uponpiston-89 which in turn forces the cap 79 to progressively-closes over the ports-until thediminished inflow pressure is balanced* by the i opposed pressure of i compressed spring"- 74. By this arrangement, 1 it can be seen that variationsin the intake 'pressureair flow above -a; predesigned degree will= cause sleeve :77 to oscillate back and forth over-tports 11 to provide a constant pressure air eflow to the interior of thecylinder 10,:and then to the aturhine. It t is to be noted, that theri'ght ends ofipthe inlet ports: 11- are tapered to avoid anyabrupt shutting oil: of ain flow.

0ther-means provided to control the turbineagainst overspeeding in: cases- -emergencyaarising due to malfunctioning of the outfiowJ-valvecontrol mechanism 22, or -from other causes. 'I'his overspeed mechanism "(Figs .1; =3", 2, 5) includes a dumpvalve 97, operable by a speed governor sensor device 198. Its purpose is .to cause pres- .Jsure air from the inlet-scroll. totbe diverted to-the-tpiston n85. Th'is will as t a consequence,-effect a rightward movement of sleeve 77-through 1piStOn:85l aCtiIlg .on piston 89 asoias to close theports 11..and *shutioff, lthe pressuretair riflowto the turbine. l l

:Inathis .overspeed protective-. means(the fitting 84 com tmunicates. the pistons cylinder 82'iby arline 9910 pne end Jr100-0fi an elongated chamber of a ball valve 101. The .-opposite-endof the: chamber communicatesv through a -fittingu102wand 1ine 103i withi thednmp :valve 97.

.rIntthe ball valve (Fig.5) atslidable pistonx blockg104 :gbiased byl a spring 105 seatsta ball 1106; in-the...valve-over lathe; inlet end. and also 1: over asnearby passage: 107. 1 The xllatter extends 01f laterally :from the. ball. valve: chamber and communicates with thesintake :scroll 14.

Durnpavalve: 97: (Fig.1 2). includes: a piston. 108aslidable -in avchamberiofythe 1 valve. Thispistonhas a conical ahead which seatst in arr-outlet opening of thepvalvei andis 1 biased ;to. seatingposition bymawspring 110. The piston "carries an operating pin .111: cthat ,projects a through the .scat opening. (The dump valve piston is pressurized to .iclosed position over its outlet by pressureflairwhich leaks :through thepassage line. 103 from port .l07 aroundrthe -ballwa1ve- 106. and block? "104 K pressure buildsiup in rtheline1103against theblojckrand ball, and serves; to seal moth communication of; passage 107 with; piston, line z 9 9. I :The.1-.arrangement ais such" that should the operating pm llltof theidllmplva v he: pressedzinwardix the pressur in line 103 will be released, andi ase 21:;QQI1SQQL1CI1Q65'5 pressure Jain. through ,passage107; willymove the; ball l06yfree of 7-0 l ine;9 9 and.will flow over line 99 to; attack the large area .-,of piston-85. The latter action,., as preyiouslyexplained, twill ef fect movement of sleeye 7.7 and a consequent shutitin 91 ofip ssu e airzt r ughzrp rts. 11 cause decelera- :tiaa i n t hine. i

' 6 T'Ihe pperatingpin "111" of the dump-valve is automatically operable by jthefspeedsensing device98"i(Fig."2); {The "latter comprises a-cup member 114 havingan .axially extending hollow shaft 115 that is carried fast-thehub 5 end oftllrbineshaft 3. Slidableinthe cupis amushroom head'116 of apiston r0d117. The 'latter is adapted-to slidejin the hollowshaft 115. Acoil spring118,=retained in-the cup-by; asnap ring1'19;" at one" end,* te nsions"the mushroom- "piston head-toward the base of cup: member 10 "114 to'cover apluralityof fly balls 120'. "The dump valve is supported axially in a wall of the turbine exhaustduct 9, and the operating-pin" 111' of-the durnp {valve normally abuts against "the exposed mushroom- "piston" head"*"116. The operation is i such that; upon" the turbine-overspeeding silfiiciently to causethe" fly balls '120to"centrifugally force the mushroom head outward from its cup; the pin lll will be depressed to operate'thc dump valve and effect the actions previously-mentioned.

Although an embodiment ofithe -invention has-been illustrated anddescribedfiin detail, it 'is to be" expressly understood that the invention isl not "limited *thereto. Various changes 'can* be 'made in the design -and-arrange ment of the parts without departing from the spirit. arid scope of the invention as the-same will -now be understood *by those skilled in the art.

What is claimedis: i p l 1; r A turbine 1 speed 'control' system including" a turbine drive; a valve for conveying fluid under pressure fronr a source to the turbinedrive, the valveincludingfluiclflow l pressure "control-means operable by the incoming "fluid under pressure to maintain a constant pressure ofthe fluid flow through the valve, speed sensing actuatorzmeans'operable-by the turbine drive above arratedspeedofthe latter, shut off fluid flow -control'means 'includedinthe valve operatively associated with the speed sensing, actuwator-means tof'shut off-=theflow of fluidmnder pressure "through thevalve, said-shut off'flow control means includingqpiston' means operable 'to shut "o'lf pressure fluid flow through the valves-spring means normally tensioning the pistonmea-ns to ine'ffectiveposition, a conduit connecting the piston means with a source of-pressurej'fluid effective 'tooperate theQ-pistori means against the tension of the spring means to effective shutofi position) blocking valve it means normally blocking flow ofp-pressure :fluid 'throughthe conduit to the piston means, and means operable by the speed sensing actuator to relievetheblocking effectof theblocking valve means so as tocause-a'tflow of pressure fluid through .the'conduit to" operatethe piston -means. 2JA turbine speedcontrohsystemincluding 'a: turbine drive, a valve for conveying fluid under pressure. from "a source -to the turbine driveithevalve including 'fiuid"'flow pressure control means operable by the incoming fluid under pressure tomaintainaconstant pressure of theflu'id flow through the valve; speed sensing actuator means'pperable bythe-turbine drive above a rated speed. ofilithe "latter, shut oif fluid flow controlmeans includedin the valve operatively associated with the speed sensingaetuator -means to shut off the flow 'of-fluid ,under pressure F60 through the valve,-saidpressurefflowcontrol means including a valve cylinder reciprocal over inlet ports .of the valve to varyxthe-pressure fluid -flow therethrough, cali- --brated spring means normallyibiasing the .v'alve cylinder ='free of the inlet ports, and-piston means operable" by pres- -sure fluid flowing-'throu'gh the-inlet ports to moveithe valve cylinder progressively over i the ports until the. inflow pressure againstthe piston balances (the .toppo'sin g .tensionof thecalibrated spring means. .3. In a pressureair ,drivenwturbine speed control .sys tem,,a turbine, a drive .shaftcan'ying theturbine,. a.first turbine. speed sensing .means centrifugally operable i by the drive shaft upon'thelatter exceeding a rated speed,

other turbine. speed. sensing means centrifugally {operable .75 hylithe sdrive shaftigpon-cthe lattertzexceeding ax-zfurthcr iratedspeed, a relay valve unit for conveying a flow of :sensing means to control the flow of pressure from the 1 {common chamber to the turbine, and the inlet valve be- 1ing responsive to the other turbine speed sensing means to shut off the flow of pressure air to the common chamber.

4. In a turbine speed control system as in claim 3,

wherein the inlet valve includes means operable by the flow of pressure air from the source to the common chambet to control the extent of flow of pressure air to the common chamber. i

5 air driven turbine speed control system comprising in cooperative combination, a turbine operable by pressure airflow, a drive shaft carrying the turbine, a rei lay valve unit for conveying a flow of pressure air from a connected source to the turbine, the relay unit including an inlet valve and an outlet valve and having an inletoutlet chamber common to both valves, the outlet valve being hydraulically operable to vary the flow of pressure air from the common chamber to the turbine upon the turbine exceeding a first rated speed, a gear pump continuously operable by the turbine drive shaft to pump hydraulic fluid from a sump to operate the outlet valve, a

speed sensing valve normally blocking hydraulic fluid flow to the outlet valve, a check valve operable by the blocked hydraulic fluid flow to pass the latter to sump, and the speed sensing valve being centrifugally operable to allow .flow of the hydraulic fluid to the outlet valve upon the turbine exceeding the rated speed.

6. An air driven turbine speed controlsystem comprising in cooperative combination, a turbine operable by pressure air flow, a drive shaft carrying the turbine, a relay valve unit for conveying a flow of pressure air from a connected source to the turbine, the relay unit including an inlet valve and an outlet valve and having an inlet-outletfchamb er common to both valves, the outlet valve being hydraulically operable to vary the flow of pressure air .from the common chamber to the turbine upon the turbine exceeding a first rated speed, a gear pump continuously operable by the turbine drive shaft to pump hydraulic fluid from a sump to operate the outlet valve, a

speed sensing valve normally blocking hydraulic fluid flow to the outlet valve, a check valve operable by the blocked hydraulic fluid flow to pass the latter sump, and the speed ,sensing valve being centrifugally operable to allow flow of the hydraulic fluid to the outlet valve upon the turbine exceeding the rated speed, the inlet valve including spring restrained means operable by inlet pressure air flow to the common chamber to vary the inlet flow to the chamber until the pressure of the inflow air to the spring restrained ,means balances the force of therestraining spring.

7. An air driven turbine speed control system comprising in cooperative combination, a turbine operable by pressureair flow, a drive shaft carrying the turbine, a

outlet chamber common to both valves, the outlet valve being hydraulically operable to vary the flow of pressure air from the common chamber to the turbine upon the turbine-exceeding a first rated speed, a gear pump continuously operable by the turbine drive shaft to pump hydraulic fluid from a sump to operate the outlet valve, a speed sensing valve normally blocking hydraulic fluid 'flow to the outlet valve, a check valve operable by the blocked hydraulic fluid flow to pass the latter to sump, and the speed sensing valve being centrifugally operable to allow flow of the hydraulic fluid to the outlet valve upon the turbine exceeding the rated speed, the inlet valve including spring restrained means'operable by inlet pressure air flow to the common chamber to vary the inlet flow to the chamber until the pressure of the inflow air to the spring restrained means'balances the force of v the restraining spring, spring restrained piston means operable by pressure air from the source to cause the spring restrained means to shut off the inlet flow to thechamber, a conduit branch from the source conveying pressure air to the piston means, a dump valve normally blocking communication of the conduit branch with the piston means, and actuator means centrifugally operable'by the turbine drive shaft to operate the dump valve to unblock communication of the conduit branch with the piston means when the turbine drive shaft exceeds a further rated 7 speed.

8. A pressure air flow control unit for communicating pressure air from a sourceto drive a prime mover, comprising an elongated cylinder having a plurality of inflow ports located ofi to one side of the center of the cylinder and aplurality of outflow ports located off to the other side of center, a pressure air inflow scroll mounted about a first end portion of the cylinder and providing communication from a connected pressure air source to the interior of thecylinder through the inflow ports, a pressure air outflow scroll mounted about an opposite second end portion of the cylinder and providing communication of pressure air flow from the interior of the cylinder through the outflow ports to an associated prime mover,

first valve means in the first end portion of the cylinder operable to control the degree of pressure air flow through the inflow ports to the interior of the cylinder, the first valve means comprising a valve sleeve slidable over the inflow ports to diminish the air flow therethrough, spring means normally biasing the valve sleeve free of the in flow ports, piston means associated for sliding the sleeve and operable by pressure air flow from within-theinterior of the cylinder to slide the sleeve against the bias of the spring means progressively over the inflow portsas the pressure flow of the inflow air increases beyond a rated maximum, and second valve means operable in the second end portion ofthe cylinder to control the extent of pressure air outflow from the interior of the cylinder through the outflow ports, the second valve means comprising a valve sleeve slidable over the outflow ports to diminish the size thereof, spring means normally biasing the valve sleeve free of the outflow ports and hydraulic piston means operable by the output of hydraulic pump means to progressively move the valve sleeve over the outflow portsagainst the bias of the last mentioned spring means.

9. The combination of a pressure air flow control unit as in claim 8 with centrifugally operable valve means interposed intermediately of the output of the hydraulic pump and the hydraulic piston and normally blocking communication of the one with the other, and means for operatively associating the centrifugally operablevalve means with the prime mover.

10. A turbine speed control system comprising valve means including a first valve member, fluid pressure responsive means to operate said first valve member so as to regulate a variable pressure fluid to a constant pressure to drive the turbine, a second valve member, speed responsive control means operable by the turbine to adjust said second valve member so as to regulate the flow of pressure fluid through the valve means inversely to the speed of the turbine after the latter exceeds a rated maximum speed, and other speed responsive control means operable by the turbine to adjust said first valve member so as to shut off the flow of pressure fluid through the valve means to the turbine after the turbine exceeds a further rated maximum speed.

11. A constant speed power apparatus comprised of a fluid-operated turbine, fluid supply means including a pressure-regulating inlet valve and an adjustable flow valve in series operatively connected to said turbine for delivering a constant-pressure variable supply of working fluid to said turbine, governor means responsive to-thespeed 9 of said turbine connected to said flow valve byhydraulic means which is pressurized by said turbine to regulate the fluid flow to said turbine and hence the speed thereof, speed responsive means actuated by said turbine operatively connected to close said pressure-regulating valve when said governored flow valve fails to operate, and said pressure regulating valve and said speed responsive means being constructed so that inlet fluid closes said pressure regulating valve when the flow valve fails to operate.

12. A speed control system comprising a turbine drive, relay conduit means for communicating pressure fluid from a source to the turbine drive, a first valve member to control an inlet to said conduit means, pressure responsive means connected downstream of said inlet'to operate said first valve member so as to reduce the fluid pressure in said conduit means to a predetermined constant pressure upon the fluid varying in pressure above a predeterminedmaximum, a second valve member to control an outlet from said conduit means, speed responsive means operable by the turbine upon the latter exceeding a predetermined speed to adjustably position said second valve member so as to vary the flow of pressure fluid from the relay conduit means to the turbine inversely as the turbine speed increases, other means, operable centrifugally by the turbine upon the latter overspeeding beyond a further predetermined maximum speed, arranged to close the first valve member so as to shut oil the flow of fluid from the source to the relay conduit means.

References Cited in the file of this patent UNITED STATES PATENTS 1,444,437 Ver Planck Feb. 6, 1923 1,669,108 Warner May 8, 1928 1,771,720 Miller July 29, 1930 1,850,133 Munzinger Mar. 22, 1932 2,095,132 Hofiman -4 Oct. 5, 1937 2,285,208 Johntz et a1. June 2, 1942 2,618,324 Jordan Nov. 18, 1952 2,670,599

Davies Mar. 2, 1954 

